| /* |
| * Intel(R) Processor Trace PMU driver for perf |
| * Copyright (c) 2013-2014, Intel Corporation. |
| * |
| * This program is free software; you can redistribute it and/or modify it |
| * under the terms and conditions of the GNU General Public License, |
| * version 2, as published by the Free Software Foundation. |
| * |
| * This program is distributed in the hope it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| * more details. |
| * |
| * Intel PT is specified in the Intel Architecture Instruction Set Extensions |
| * Programming Reference: |
| * http://software.intel.com/en-us/intel-isa-extensions |
| */ |
| |
| #undef DEBUG |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| |
| #include <linux/types.h> |
| #include <linux/slab.h> |
| #include <linux/device.h> |
| |
| #include <asm/perf_event.h> |
| #include <asm/insn.h> |
| #include <asm/io.h> |
| #include <asm/intel_pt.h> |
| |
| #include "../perf_event.h" |
| #include "pt.h" |
| |
| static DEFINE_PER_CPU(struct pt, pt_ctx); |
| |
| static struct pt_pmu pt_pmu; |
| |
| enum cpuid_regs { |
| CR_EAX = 0, |
| CR_ECX, |
| CR_EDX, |
| CR_EBX |
| }; |
| |
| /* |
| * Capabilities of Intel PT hardware, such as number of address bits or |
| * supported output schemes, are cached and exported to userspace as "caps" |
| * attribute group of pt pmu device |
| * (/sys/bus/event_source/devices/intel_pt/caps/) so that userspace can store |
| * relevant bits together with intel_pt traces. |
| * |
| * These are necessary for both trace decoding (payloads_lip, contains address |
| * width encoded in IP-related packets), and event configuration (bitmasks with |
| * permitted values for certain bit fields). |
| */ |
| #define PT_CAP(_n, _l, _r, _m) \ |
| [PT_CAP_ ## _n] = { .name = __stringify(_n), .leaf = _l, \ |
| .reg = _r, .mask = _m } |
| |
| static struct pt_cap_desc { |
| const char *name; |
| u32 leaf; |
| u8 reg; |
| u32 mask; |
| } pt_caps[] = { |
| PT_CAP(max_subleaf, 0, CR_EAX, 0xffffffff), |
| PT_CAP(cr3_filtering, 0, CR_EBX, BIT(0)), |
| PT_CAP(psb_cyc, 0, CR_EBX, BIT(1)), |
| PT_CAP(mtc, 0, CR_EBX, BIT(3)), |
| PT_CAP(topa_output, 0, CR_ECX, BIT(0)), |
| PT_CAP(topa_multiple_entries, 0, CR_ECX, BIT(1)), |
| PT_CAP(single_range_output, 0, CR_ECX, BIT(2)), |
| PT_CAP(payloads_lip, 0, CR_ECX, BIT(31)), |
| PT_CAP(mtc_periods, 1, CR_EAX, 0xffff0000), |
| PT_CAP(cycle_thresholds, 1, CR_EBX, 0xffff), |
| PT_CAP(psb_periods, 1, CR_EBX, 0xffff0000), |
| }; |
| |
| static u32 pt_cap_get(enum pt_capabilities cap) |
| { |
| struct pt_cap_desc *cd = &pt_caps[cap]; |
| u32 c = pt_pmu.caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg]; |
| unsigned int shift = __ffs(cd->mask); |
| |
| return (c & cd->mask) >> shift; |
| } |
| |
| static ssize_t pt_cap_show(struct device *cdev, |
| struct device_attribute *attr, |
| char *buf) |
| { |
| struct dev_ext_attribute *ea = |
| container_of(attr, struct dev_ext_attribute, attr); |
| enum pt_capabilities cap = (long)ea->var; |
| |
| return snprintf(buf, PAGE_SIZE, "%x\n", pt_cap_get(cap)); |
| } |
| |
| static struct attribute_group pt_cap_group = { |
| .name = "caps", |
| }; |
| |
| PMU_FORMAT_ATTR(cyc, "config:1" ); |
| PMU_FORMAT_ATTR(mtc, "config:9" ); |
| PMU_FORMAT_ATTR(tsc, "config:10" ); |
| PMU_FORMAT_ATTR(noretcomp, "config:11" ); |
| PMU_FORMAT_ATTR(mtc_period, "config:14-17" ); |
| PMU_FORMAT_ATTR(cyc_thresh, "config:19-22" ); |
| PMU_FORMAT_ATTR(psb_period, "config:24-27" ); |
| |
| static struct attribute *pt_formats_attr[] = { |
| &format_attr_cyc.attr, |
| &format_attr_mtc.attr, |
| &format_attr_tsc.attr, |
| &format_attr_noretcomp.attr, |
| &format_attr_mtc_period.attr, |
| &format_attr_cyc_thresh.attr, |
| &format_attr_psb_period.attr, |
| NULL, |
| }; |
| |
| static struct attribute_group pt_format_group = { |
| .name = "format", |
| .attrs = pt_formats_attr, |
| }; |
| |
| static const struct attribute_group *pt_attr_groups[] = { |
| &pt_cap_group, |
| &pt_format_group, |
| NULL, |
| }; |
| |
| static int __init pt_pmu_hw_init(void) |
| { |
| struct dev_ext_attribute *de_attrs; |
| struct attribute **attrs; |
| size_t size; |
| u64 reg; |
| int ret; |
| long i; |
| |
| if (boot_cpu_has(X86_FEATURE_VMX)) { |
| /* |
| * Intel SDM, 36.5 "Tracing post-VMXON" says that |
| * "IA32_VMX_MISC[bit 14]" being 1 means PT can trace |
| * post-VMXON. |
| */ |
| rdmsrl(MSR_IA32_VMX_MISC, reg); |
| if (reg & BIT(14)) |
| pt_pmu.vmx = true; |
| } |
| |
| attrs = NULL; |
| |
| for (i = 0; i < PT_CPUID_LEAVES; i++) { |
| cpuid_count(20, i, |
| &pt_pmu.caps[CR_EAX + i*PT_CPUID_REGS_NUM], |
| &pt_pmu.caps[CR_EBX + i*PT_CPUID_REGS_NUM], |
| &pt_pmu.caps[CR_ECX + i*PT_CPUID_REGS_NUM], |
| &pt_pmu.caps[CR_EDX + i*PT_CPUID_REGS_NUM]); |
| } |
| |
| ret = -ENOMEM; |
| size = sizeof(struct attribute *) * (ARRAY_SIZE(pt_caps)+1); |
| attrs = kzalloc(size, GFP_KERNEL); |
| if (!attrs) |
| goto fail; |
| |
| size = sizeof(struct dev_ext_attribute) * (ARRAY_SIZE(pt_caps)+1); |
| de_attrs = kzalloc(size, GFP_KERNEL); |
| if (!de_attrs) |
| goto fail; |
| |
| for (i = 0; i < ARRAY_SIZE(pt_caps); i++) { |
| struct dev_ext_attribute *de_attr = de_attrs + i; |
| |
| de_attr->attr.attr.name = pt_caps[i].name; |
| |
| sysfs_attr_init(&de_attr->attr.attr); |
| |
| de_attr->attr.attr.mode = S_IRUGO; |
| de_attr->attr.show = pt_cap_show; |
| de_attr->var = (void *)i; |
| |
| attrs[i] = &de_attr->attr.attr; |
| } |
| |
| pt_cap_group.attrs = attrs; |
| |
| return 0; |
| |
| fail: |
| kfree(attrs); |
| |
| return ret; |
| } |
| |
| #define RTIT_CTL_CYC_PSB (RTIT_CTL_CYCLEACC | \ |
| RTIT_CTL_CYC_THRESH | \ |
| RTIT_CTL_PSB_FREQ) |
| |
| #define RTIT_CTL_MTC (RTIT_CTL_MTC_EN | \ |
| RTIT_CTL_MTC_RANGE) |
| |
| #define PT_CONFIG_MASK (RTIT_CTL_TSC_EN | \ |
| RTIT_CTL_DISRETC | \ |
| RTIT_CTL_CYC_PSB | \ |
| RTIT_CTL_MTC) |
| |
| static bool pt_event_valid(struct perf_event *event) |
| { |
| u64 config = event->attr.config; |
| u64 allowed, requested; |
| |
| if ((config & PT_CONFIG_MASK) != config) |
| return false; |
| |
| if (config & RTIT_CTL_CYC_PSB) { |
| if (!pt_cap_get(PT_CAP_psb_cyc)) |
| return false; |
| |
| allowed = pt_cap_get(PT_CAP_psb_periods); |
| requested = (config & RTIT_CTL_PSB_FREQ) >> |
| RTIT_CTL_PSB_FREQ_OFFSET; |
| if (requested && (!(allowed & BIT(requested)))) |
| return false; |
| |
| allowed = pt_cap_get(PT_CAP_cycle_thresholds); |
| requested = (config & RTIT_CTL_CYC_THRESH) >> |
| RTIT_CTL_CYC_THRESH_OFFSET; |
| if (requested && (!(allowed & BIT(requested)))) |
| return false; |
| } |
| |
| if (config & RTIT_CTL_MTC) { |
| /* |
| * In the unlikely case that CPUID lists valid mtc periods, |
| * but not the mtc capability, drop out here. |
| * |
| * Spec says that setting mtc period bits while mtc bit in |
| * CPUID is 0 will #GP, so better safe than sorry. |
| */ |
| if (!pt_cap_get(PT_CAP_mtc)) |
| return false; |
| |
| allowed = pt_cap_get(PT_CAP_mtc_periods); |
| if (!allowed) |
| return false; |
| |
| requested = (config & RTIT_CTL_MTC_RANGE) >> |
| RTIT_CTL_MTC_RANGE_OFFSET; |
| |
| if (!(allowed & BIT(requested))) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| /* |
| * PT configuration helpers |
| * These all are cpu affine and operate on a local PT |
| */ |
| |
| static void pt_config(struct perf_event *event) |
| { |
| u64 reg; |
| |
| if (!event->hw.itrace_started) { |
| event->hw.itrace_started = 1; |
| wrmsrl(MSR_IA32_RTIT_STATUS, 0); |
| } |
| |
| reg = RTIT_CTL_TOPA | RTIT_CTL_BRANCH_EN | RTIT_CTL_TRACEEN; |
| |
| if (!event->attr.exclude_kernel) |
| reg |= RTIT_CTL_OS; |
| if (!event->attr.exclude_user) |
| reg |= RTIT_CTL_USR; |
| |
| reg |= (event->attr.config & PT_CONFIG_MASK); |
| |
| event->hw.config = reg; |
| wrmsrl(MSR_IA32_RTIT_CTL, reg); |
| } |
| |
| static void pt_config_stop(struct perf_event *event) |
| { |
| u64 ctl = READ_ONCE(event->hw.config); |
| |
| /* may be already stopped by a PMI */ |
| if (!(ctl & RTIT_CTL_TRACEEN)) |
| return; |
| |
| ctl &= ~RTIT_CTL_TRACEEN; |
| wrmsrl(MSR_IA32_RTIT_CTL, ctl); |
| |
| WRITE_ONCE(event->hw.config, ctl); |
| |
| /* |
| * A wrmsr that disables trace generation serializes other PT |
| * registers and causes all data packets to be written to memory, |
| * but a fence is required for the data to become globally visible. |
| * |
| * The below WMB, separating data store and aux_head store matches |
| * the consumer's RMB that separates aux_head load and data load. |
| */ |
| wmb(); |
| } |
| |
| static void pt_config_buffer(void *buf, unsigned int topa_idx, |
| unsigned int output_off) |
| { |
| u64 reg; |
| |
| wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, virt_to_phys(buf)); |
| |
| reg = 0x7f | ((u64)topa_idx << 7) | ((u64)output_off << 32); |
| |
| wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg); |
| } |
| |
| /* |
| * Keep ToPA table-related metadata on the same page as the actual table, |
| * taking up a few words from the top |
| */ |
| |
| #define TENTS_PER_PAGE (((PAGE_SIZE - 40) / sizeof(struct topa_entry)) - 1) |
| |
| /** |
| * struct topa - page-sized ToPA table with metadata at the top |
| * @table: actual ToPA table entries, as understood by PT hardware |
| * @list: linkage to struct pt_buffer's list of tables |
| * @phys: physical address of this page |
| * @offset: offset of the first entry in this table in the buffer |
| * @size: total size of all entries in this table |
| * @last: index of the last initialized entry in this table |
| */ |
| struct topa { |
| struct topa_entry table[TENTS_PER_PAGE]; |
| struct list_head list; |
| u64 phys; |
| u64 offset; |
| size_t size; |
| int last; |
| }; |
| |
| /* make -1 stand for the last table entry */ |
| #define TOPA_ENTRY(t, i) ((i) == -1 ? &(t)->table[(t)->last] : &(t)->table[(i)]) |
| |
| /** |
| * topa_alloc() - allocate page-sized ToPA table |
| * @cpu: CPU on which to allocate. |
| * @gfp: Allocation flags. |
| * |
| * Return: On success, return the pointer to ToPA table page. |
| */ |
| static struct topa *topa_alloc(int cpu, gfp_t gfp) |
| { |
| int node = cpu_to_node(cpu); |
| struct topa *topa; |
| struct page *p; |
| |
| p = alloc_pages_node(node, gfp | __GFP_ZERO, 0); |
| if (!p) |
| return NULL; |
| |
| topa = page_address(p); |
| topa->last = 0; |
| topa->phys = page_to_phys(p); |
| |
| /* |
| * In case of singe-entry ToPA, always put the self-referencing END |
| * link as the 2nd entry in the table |
| */ |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries)) { |
| TOPA_ENTRY(topa, 1)->base = topa->phys >> TOPA_SHIFT; |
| TOPA_ENTRY(topa, 1)->end = 1; |
| } |
| |
| return topa; |
| } |
| |
| /** |
| * topa_free() - free a page-sized ToPA table |
| * @topa: Table to deallocate. |
| */ |
| static void topa_free(struct topa *topa) |
| { |
| free_page((unsigned long)topa); |
| } |
| |
| /** |
| * topa_insert_table() - insert a ToPA table into a buffer |
| * @buf: PT buffer that's being extended. |
| * @topa: New topa table to be inserted. |
| * |
| * If it's the first table in this buffer, set up buffer's pointers |
| * accordingly; otherwise, add a END=1 link entry to @topa to the current |
| * "last" table and adjust the last table pointer to @topa. |
| */ |
| static void topa_insert_table(struct pt_buffer *buf, struct topa *topa) |
| { |
| struct topa *last = buf->last; |
| |
| list_add_tail(&topa->list, &buf->tables); |
| |
| if (!buf->first) { |
| buf->first = buf->last = buf->cur = topa; |
| return; |
| } |
| |
| topa->offset = last->offset + last->size; |
| buf->last = topa; |
| |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries)) |
| return; |
| |
| BUG_ON(last->last != TENTS_PER_PAGE - 1); |
| |
| TOPA_ENTRY(last, -1)->base = topa->phys >> TOPA_SHIFT; |
| TOPA_ENTRY(last, -1)->end = 1; |
| } |
| |
| /** |
| * topa_table_full() - check if a ToPA table is filled up |
| * @topa: ToPA table. |
| */ |
| static bool topa_table_full(struct topa *topa) |
| { |
| /* single-entry ToPA is a special case */ |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries)) |
| return !!topa->last; |
| |
| return topa->last == TENTS_PER_PAGE - 1; |
| } |
| |
| /** |
| * topa_insert_pages() - create a list of ToPA tables |
| * @buf: PT buffer being initialized. |
| * @gfp: Allocation flags. |
| * |
| * This initializes a list of ToPA tables with entries from |
| * the data_pages provided by rb_alloc_aux(). |
| * |
| * Return: 0 on success or error code. |
| */ |
| static int topa_insert_pages(struct pt_buffer *buf, gfp_t gfp) |
| { |
| struct topa *topa = buf->last; |
| int order = 0; |
| struct page *p; |
| |
| p = virt_to_page(buf->data_pages[buf->nr_pages]); |
| if (PagePrivate(p)) |
| order = page_private(p); |
| |
| if (topa_table_full(topa)) { |
| topa = topa_alloc(buf->cpu, gfp); |
| if (!topa) |
| return -ENOMEM; |
| |
| topa_insert_table(buf, topa); |
| } |
| |
| TOPA_ENTRY(topa, -1)->base = page_to_phys(p) >> TOPA_SHIFT; |
| TOPA_ENTRY(topa, -1)->size = order; |
| if (!buf->snapshot && !pt_cap_get(PT_CAP_topa_multiple_entries)) { |
| TOPA_ENTRY(topa, -1)->intr = 1; |
| TOPA_ENTRY(topa, -1)->stop = 1; |
| } |
| |
| topa->last++; |
| topa->size += sizes(order); |
| |
| buf->nr_pages += 1ul << order; |
| |
| return 0; |
| } |
| |
| /** |
| * pt_topa_dump() - print ToPA tables and their entries |
| * @buf: PT buffer. |
| */ |
| static void pt_topa_dump(struct pt_buffer *buf) |
| { |
| struct topa *topa; |
| |
| list_for_each_entry(topa, &buf->tables, list) { |
| int i; |
| |
| pr_debug("# table @%p (%016Lx), off %llx size %zx\n", topa->table, |
| topa->phys, topa->offset, topa->size); |
| for (i = 0; i < TENTS_PER_PAGE; i++) { |
| pr_debug("# entry @%p (%lx sz %u %c%c%c) raw=%16llx\n", |
| &topa->table[i], |
| (unsigned long)topa->table[i].base << TOPA_SHIFT, |
| sizes(topa->table[i].size), |
| topa->table[i].end ? 'E' : ' ', |
| topa->table[i].intr ? 'I' : ' ', |
| topa->table[i].stop ? 'S' : ' ', |
| *(u64 *)&topa->table[i]); |
| if ((pt_cap_get(PT_CAP_topa_multiple_entries) && |
| topa->table[i].stop) || |
| topa->table[i].end) |
| break; |
| } |
| } |
| } |
| |
| /** |
| * pt_buffer_advance() - advance to the next output region |
| * @buf: PT buffer. |
| * |
| * Advance the current pointers in the buffer to the next ToPA entry. |
| */ |
| static void pt_buffer_advance(struct pt_buffer *buf) |
| { |
| buf->output_off = 0; |
| buf->cur_idx++; |
| |
| if (buf->cur_idx == buf->cur->last) { |
| if (buf->cur == buf->last) |
| buf->cur = buf->first; |
| else |
| buf->cur = list_entry(buf->cur->list.next, struct topa, |
| list); |
| buf->cur_idx = 0; |
| } |
| } |
| |
| /** |
| * pt_update_head() - calculate current offsets and sizes |
| * @pt: Per-cpu pt context. |
| * |
| * Update buffer's current write pointer position and data size. |
| */ |
| static void pt_update_head(struct pt *pt) |
| { |
| struct pt_buffer *buf = perf_get_aux(&pt->handle); |
| u64 topa_idx, base, old; |
| |
| /* offset of the first region in this table from the beginning of buf */ |
| base = buf->cur->offset + buf->output_off; |
| |
| /* offset of the current output region within this table */ |
| for (topa_idx = 0; topa_idx < buf->cur_idx; topa_idx++) |
| base += sizes(buf->cur->table[topa_idx].size); |
| |
| if (buf->snapshot) { |
| local_set(&buf->data_size, base); |
| } else { |
| old = (local64_xchg(&buf->head, base) & |
| ((buf->nr_pages << PAGE_SHIFT) - 1)); |
| if (base < old) |
| base += buf->nr_pages << PAGE_SHIFT; |
| |
| local_add(base - old, &buf->data_size); |
| } |
| } |
| |
| /** |
| * pt_buffer_region() - obtain current output region's address |
| * @buf: PT buffer. |
| */ |
| static void *pt_buffer_region(struct pt_buffer *buf) |
| { |
| return phys_to_virt(buf->cur->table[buf->cur_idx].base << TOPA_SHIFT); |
| } |
| |
| /** |
| * pt_buffer_region_size() - obtain current output region's size |
| * @buf: PT buffer. |
| */ |
| static size_t pt_buffer_region_size(struct pt_buffer *buf) |
| { |
| return sizes(buf->cur->table[buf->cur_idx].size); |
| } |
| |
| /** |
| * pt_handle_status() - take care of possible status conditions |
| * @pt: Per-cpu pt context. |
| */ |
| static void pt_handle_status(struct pt *pt) |
| { |
| struct pt_buffer *buf = perf_get_aux(&pt->handle); |
| int advance = 0; |
| u64 status; |
| |
| rdmsrl(MSR_IA32_RTIT_STATUS, status); |
| |
| if (status & RTIT_STATUS_ERROR) { |
| pr_err_ratelimited("ToPA ERROR encountered, trying to recover\n"); |
| pt_topa_dump(buf); |
| status &= ~RTIT_STATUS_ERROR; |
| } |
| |
| if (status & RTIT_STATUS_STOPPED) { |
| status &= ~RTIT_STATUS_STOPPED; |
| |
| /* |
| * On systems that only do single-entry ToPA, hitting STOP |
| * means we are already losing data; need to let the decoder |
| * know. |
| */ |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries) || |
| buf->output_off == sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size)) { |
| local_inc(&buf->lost); |
| advance++; |
| } |
| } |
| |
| /* |
| * Also on single-entry ToPA implementations, interrupt will come |
| * before the output reaches its output region's boundary. |
| */ |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries) && !buf->snapshot && |
| pt_buffer_region_size(buf) - buf->output_off <= TOPA_PMI_MARGIN) { |
| void *head = pt_buffer_region(buf); |
| |
| /* everything within this margin needs to be zeroed out */ |
| memset(head + buf->output_off, 0, |
| pt_buffer_region_size(buf) - |
| buf->output_off); |
| advance++; |
| } |
| |
| if (advance) |
| pt_buffer_advance(buf); |
| |
| wrmsrl(MSR_IA32_RTIT_STATUS, status); |
| } |
| |
| /** |
| * pt_read_offset() - translate registers into buffer pointers |
| * @buf: PT buffer. |
| * |
| * Set buffer's output pointers from MSR values. |
| */ |
| static void pt_read_offset(struct pt_buffer *buf) |
| { |
| u64 offset, base_topa; |
| |
| rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, base_topa); |
| buf->cur = phys_to_virt(base_topa); |
| |
| rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, offset); |
| /* offset within current output region */ |
| buf->output_off = offset >> 32; |
| /* index of current output region within this table */ |
| buf->cur_idx = (offset & 0xffffff80) >> 7; |
| } |
| |
| /** |
| * pt_topa_next_entry() - obtain index of the first page in the next ToPA entry |
| * @buf: PT buffer. |
| * @pg: Page offset in the buffer. |
| * |
| * When advancing to the next output region (ToPA entry), given a page offset |
| * into the buffer, we need to find the offset of the first page in the next |
| * region. |
| */ |
| static unsigned int pt_topa_next_entry(struct pt_buffer *buf, unsigned int pg) |
| { |
| struct topa_entry *te = buf->topa_index[pg]; |
| |
| /* one region */ |
| if (buf->first == buf->last && buf->first->last == 1) |
| return pg; |
| |
| do { |
| pg++; |
| pg &= buf->nr_pages - 1; |
| } while (buf->topa_index[pg] == te); |
| |
| return pg; |
| } |
| |
| /** |
| * pt_buffer_reset_markers() - place interrupt and stop bits in the buffer |
| * @buf: PT buffer. |
| * @handle: Current output handle. |
| * |
| * Place INT and STOP marks to prevent overwriting old data that the consumer |
| * hasn't yet collected and waking up the consumer after a certain fraction of |
| * the buffer has filled up. Only needed and sensible for non-snapshot counters. |
| * |
| * This obviously relies on buf::head to figure out buffer markers, so it has |
| * to be called after pt_buffer_reset_offsets() and before the hardware tracing |
| * is enabled. |
| */ |
| static int pt_buffer_reset_markers(struct pt_buffer *buf, |
| struct perf_output_handle *handle) |
| |
| { |
| unsigned long head = local64_read(&buf->head); |
| unsigned long idx, npages, wakeup; |
| |
| /* can't stop in the middle of an output region */ |
| if (buf->output_off + handle->size + 1 < |
| sizes(TOPA_ENTRY(buf->cur, buf->cur_idx)->size)) |
| return -EINVAL; |
| |
| |
| /* single entry ToPA is handled by marking all regions STOP=1 INT=1 */ |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries)) |
| return 0; |
| |
| /* clear STOP and INT from current entry */ |
| buf->topa_index[buf->stop_pos]->stop = 0; |
| buf->topa_index[buf->intr_pos]->intr = 0; |
| |
| /* how many pages till the STOP marker */ |
| npages = handle->size >> PAGE_SHIFT; |
| |
| /* if it's on a page boundary, fill up one more page */ |
| if (!offset_in_page(head + handle->size + 1)) |
| npages++; |
| |
| idx = (head >> PAGE_SHIFT) + npages; |
| idx &= buf->nr_pages - 1; |
| buf->stop_pos = idx; |
| |
| wakeup = handle->wakeup >> PAGE_SHIFT; |
| |
| /* in the worst case, wake up the consumer one page before hard stop */ |
| idx = (head >> PAGE_SHIFT) + npages - 1; |
| if (idx > wakeup) |
| idx = wakeup; |
| |
| idx &= buf->nr_pages - 1; |
| buf->intr_pos = idx; |
| |
| buf->topa_index[buf->stop_pos]->stop = 1; |
| buf->topa_index[buf->intr_pos]->intr = 1; |
| |
| return 0; |
| } |
| |
| /** |
| * pt_buffer_setup_topa_index() - build topa_index[] table of regions |
| * @buf: PT buffer. |
| * |
| * topa_index[] references output regions indexed by offset into the |
| * buffer for purposes of quick reverse lookup. |
| */ |
| static void pt_buffer_setup_topa_index(struct pt_buffer *buf) |
| { |
| struct topa *cur = buf->first, *prev = buf->last; |
| struct topa_entry *te_cur = TOPA_ENTRY(cur, 0), |
| *te_prev = TOPA_ENTRY(prev, prev->last - 1); |
| int pg = 0, idx = 0; |
| |
| while (pg < buf->nr_pages) { |
| int tidx; |
| |
| /* pages within one topa entry */ |
| for (tidx = 0; tidx < 1 << te_cur->size; tidx++, pg++) |
| buf->topa_index[pg] = te_prev; |
| |
| te_prev = te_cur; |
| |
| if (idx == cur->last - 1) { |
| /* advance to next topa table */ |
| idx = 0; |
| cur = list_entry(cur->list.next, struct topa, list); |
| } else { |
| idx++; |
| } |
| te_cur = TOPA_ENTRY(cur, idx); |
| } |
| |
| } |
| |
| /** |
| * pt_buffer_reset_offsets() - adjust buffer's write pointers from aux_head |
| * @buf: PT buffer. |
| * @head: Write pointer (aux_head) from AUX buffer. |
| * |
| * Find the ToPA table and entry corresponding to given @head and set buffer's |
| * "current" pointers accordingly. This is done after we have obtained the |
| * current aux_head position from a successful call to perf_aux_output_begin() |
| * to make sure the hardware is writing to the right place. |
| * |
| * This function modifies buf::{cur,cur_idx,output_off} that will be programmed |
| * into PT msrs when the tracing is enabled and buf::head and buf::data_size, |
| * which are used to determine INT and STOP markers' locations by a subsequent |
| * call to pt_buffer_reset_markers(). |
| */ |
| static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head) |
| { |
| int pg; |
| |
| if (buf->snapshot) |
| head &= (buf->nr_pages << PAGE_SHIFT) - 1; |
| |
| pg = (head >> PAGE_SHIFT) & (buf->nr_pages - 1); |
| pg = pt_topa_next_entry(buf, pg); |
| |
| buf->cur = (struct topa *)((unsigned long)buf->topa_index[pg] & PAGE_MASK); |
| buf->cur_idx = ((unsigned long)buf->topa_index[pg] - |
| (unsigned long)buf->cur) / sizeof(struct topa_entry); |
| buf->output_off = head & (sizes(buf->cur->table[buf->cur_idx].size) - 1); |
| |
| local64_set(&buf->head, head); |
| local_set(&buf->data_size, 0); |
| } |
| |
| /** |
| * pt_buffer_fini_topa() - deallocate ToPA structure of a buffer |
| * @buf: PT buffer. |
| */ |
| static void pt_buffer_fini_topa(struct pt_buffer *buf) |
| { |
| struct topa *topa, *iter; |
| |
| list_for_each_entry_safe(topa, iter, &buf->tables, list) { |
| /* |
| * right now, this is in free_aux() path only, so |
| * no need to unlink this table from the list |
| */ |
| topa_free(topa); |
| } |
| } |
| |
| /** |
| * pt_buffer_init_topa() - initialize ToPA table for pt buffer |
| * @buf: PT buffer. |
| * @size: Total size of all regions within this ToPA. |
| * @gfp: Allocation flags. |
| */ |
| static int pt_buffer_init_topa(struct pt_buffer *buf, unsigned long nr_pages, |
| gfp_t gfp) |
| { |
| struct topa *topa; |
| int err; |
| |
| topa = topa_alloc(buf->cpu, gfp); |
| if (!topa) |
| return -ENOMEM; |
| |
| topa_insert_table(buf, topa); |
| |
| while (buf->nr_pages < nr_pages) { |
| err = topa_insert_pages(buf, gfp); |
| if (err) { |
| pt_buffer_fini_topa(buf); |
| return -ENOMEM; |
| } |
| } |
| |
| pt_buffer_setup_topa_index(buf); |
| |
| /* link last table to the first one, unless we're double buffering */ |
| if (pt_cap_get(PT_CAP_topa_multiple_entries)) { |
| TOPA_ENTRY(buf->last, -1)->base = buf->first->phys >> TOPA_SHIFT; |
| TOPA_ENTRY(buf->last, -1)->end = 1; |
| } |
| |
| pt_topa_dump(buf); |
| return 0; |
| } |
| |
| /** |
| * pt_buffer_setup_aux() - set up topa tables for a PT buffer |
| * @cpu: Cpu on which to allocate, -1 means current. |
| * @pages: Array of pointers to buffer pages passed from perf core. |
| * @nr_pages: Number of pages in the buffer. |
| * @snapshot: If this is a snapshot/overwrite counter. |
| * |
| * This is a pmu::setup_aux callback that sets up ToPA tables and all the |
| * bookkeeping for an AUX buffer. |
| * |
| * Return: Our private PT buffer structure. |
| */ |
| static void * |
| pt_buffer_setup_aux(int cpu, void **pages, int nr_pages, bool snapshot) |
| { |
| struct pt_buffer *buf; |
| int node, ret; |
| |
| if (!nr_pages) |
| return NULL; |
| |
| if (cpu == -1) |
| cpu = raw_smp_processor_id(); |
| node = cpu_to_node(cpu); |
| |
| buf = kzalloc_node(offsetof(struct pt_buffer, topa_index[nr_pages]), |
| GFP_KERNEL, node); |
| if (!buf) |
| return NULL; |
| |
| buf->cpu = cpu; |
| buf->snapshot = snapshot; |
| buf->data_pages = pages; |
| |
| INIT_LIST_HEAD(&buf->tables); |
| |
| ret = pt_buffer_init_topa(buf, nr_pages, GFP_KERNEL); |
| if (ret) { |
| kfree(buf); |
| return NULL; |
| } |
| |
| return buf; |
| } |
| |
| /** |
| * pt_buffer_free_aux() - perf AUX deallocation path callback |
| * @data: PT buffer. |
| */ |
| static void pt_buffer_free_aux(void *data) |
| { |
| struct pt_buffer *buf = data; |
| |
| pt_buffer_fini_topa(buf); |
| kfree(buf); |
| } |
| |
| /** |
| * pt_buffer_is_full() - check if the buffer is full |
| * @buf: PT buffer. |
| * @pt: Per-cpu pt handle. |
| * |
| * If the user hasn't read data from the output region that aux_head |
| * points to, the buffer is considered full: the user needs to read at |
| * least this region and update aux_tail to point past it. |
| */ |
| static bool pt_buffer_is_full(struct pt_buffer *buf, struct pt *pt) |
| { |
| if (buf->snapshot) |
| return false; |
| |
| if (local_read(&buf->data_size) >= pt->handle.size) |
| return true; |
| |
| return false; |
| } |
| |
| /** |
| * intel_pt_interrupt() - PT PMI handler |
| */ |
| void intel_pt_interrupt(void) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| struct pt_buffer *buf; |
| struct perf_event *event = pt->handle.event; |
| |
| /* |
| * There may be a dangling PT bit in the interrupt status register |
| * after PT has been disabled by pt_event_stop(). Make sure we don't |
| * do anything (particularly, re-enable) for this event here. |
| */ |
| if (!ACCESS_ONCE(pt->handle_nmi)) |
| return; |
| |
| /* |
| * If VMX is on and PT does not support it, don't touch anything. |
| */ |
| if (READ_ONCE(pt->vmx_on)) |
| return; |
| |
| if (!event) |
| return; |
| |
| pt_config_stop(event); |
| |
| buf = perf_get_aux(&pt->handle); |
| if (!buf) |
| return; |
| |
| pt_read_offset(buf); |
| |
| pt_handle_status(pt); |
| |
| pt_update_head(pt); |
| |
| perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0), |
| local_xchg(&buf->lost, 0)); |
| |
| if (!event->hw.state) { |
| int ret; |
| |
| buf = perf_aux_output_begin(&pt->handle, event); |
| if (!buf) { |
| event->hw.state = PERF_HES_STOPPED; |
| return; |
| } |
| |
| pt_buffer_reset_offsets(buf, pt->handle.head); |
| /* snapshot counters don't use PMI, so it's safe */ |
| ret = pt_buffer_reset_markers(buf, &pt->handle); |
| if (ret) { |
| perf_aux_output_end(&pt->handle, 0, true); |
| return; |
| } |
| |
| pt_config_buffer(buf->cur->table, buf->cur_idx, |
| buf->output_off); |
| pt_config(event); |
| } |
| } |
| |
| void intel_pt_handle_vmx(int on) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| struct perf_event *event; |
| unsigned long flags; |
| |
| /* PT plays nice with VMX, do nothing */ |
| if (pt_pmu.vmx) |
| return; |
| |
| /* |
| * VMXON will clear RTIT_CTL.TraceEn; we need to make |
| * sure to not try to set it while VMX is on. Disable |
| * interrupts to avoid racing with pmu callbacks; |
| * concurrent PMI should be handled fine. |
| */ |
| local_irq_save(flags); |
| WRITE_ONCE(pt->vmx_on, on); |
| |
| if (on) { |
| /* prevent pt_config_stop() from writing RTIT_CTL */ |
| event = pt->handle.event; |
| if (event) |
| event->hw.config = 0; |
| } |
| local_irq_restore(flags); |
| } |
| EXPORT_SYMBOL_GPL(intel_pt_handle_vmx); |
| |
| /* |
| * PMU callbacks |
| */ |
| |
| static void pt_event_start(struct perf_event *event, int mode) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| struct pt_buffer *buf = perf_get_aux(&pt->handle); |
| |
| if (READ_ONCE(pt->vmx_on)) |
| return; |
| |
| if (!buf || pt_buffer_is_full(buf, pt)) { |
| event->hw.state = PERF_HES_STOPPED; |
| return; |
| } |
| |
| ACCESS_ONCE(pt->handle_nmi) = 1; |
| event->hw.state = 0; |
| |
| pt_config_buffer(buf->cur->table, buf->cur_idx, |
| buf->output_off); |
| pt_config(event); |
| } |
| |
| static void pt_event_stop(struct perf_event *event, int mode) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| |
| /* |
| * Protect against the PMI racing with disabling wrmsr, |
| * see comment in intel_pt_interrupt(). |
| */ |
| ACCESS_ONCE(pt->handle_nmi) = 0; |
| |
| pt_config_stop(event); |
| |
| if (event->hw.state == PERF_HES_STOPPED) |
| return; |
| |
| event->hw.state = PERF_HES_STOPPED; |
| |
| if (mode & PERF_EF_UPDATE) { |
| struct pt_buffer *buf = perf_get_aux(&pt->handle); |
| |
| if (!buf) |
| return; |
| |
| if (WARN_ON_ONCE(pt->handle.event != event)) |
| return; |
| |
| pt_read_offset(buf); |
| |
| pt_handle_status(pt); |
| |
| pt_update_head(pt); |
| } |
| } |
| |
| static void pt_event_del(struct perf_event *event, int mode) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| struct pt_buffer *buf; |
| |
| pt_event_stop(event, PERF_EF_UPDATE); |
| |
| buf = perf_get_aux(&pt->handle); |
| |
| if (buf) { |
| if (buf->snapshot) |
| pt->handle.head = |
| local_xchg(&buf->data_size, |
| buf->nr_pages << PAGE_SHIFT); |
| perf_aux_output_end(&pt->handle, local_xchg(&buf->data_size, 0), |
| local_xchg(&buf->lost, 0)); |
| } |
| } |
| |
| static int pt_event_add(struct perf_event *event, int mode) |
| { |
| struct pt_buffer *buf; |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| struct hw_perf_event *hwc = &event->hw; |
| int ret = -EBUSY; |
| |
| if (pt->handle.event) |
| goto fail; |
| |
| buf = perf_aux_output_begin(&pt->handle, event); |
| ret = -EINVAL; |
| if (!buf) |
| goto fail_stop; |
| |
| pt_buffer_reset_offsets(buf, pt->handle.head); |
| if (!buf->snapshot) { |
| ret = pt_buffer_reset_markers(buf, &pt->handle); |
| if (ret) |
| goto fail_end_stop; |
| } |
| |
| if (mode & PERF_EF_START) { |
| pt_event_start(event, 0); |
| ret = -EBUSY; |
| if (hwc->state == PERF_HES_STOPPED) |
| goto fail_end_stop; |
| } else { |
| hwc->state = PERF_HES_STOPPED; |
| } |
| |
| return 0; |
| |
| fail_end_stop: |
| perf_aux_output_end(&pt->handle, 0, true); |
| fail_stop: |
| hwc->state = PERF_HES_STOPPED; |
| fail: |
| return ret; |
| } |
| |
| static void pt_event_read(struct perf_event *event) |
| { |
| } |
| |
| static void pt_event_destroy(struct perf_event *event) |
| { |
| x86_del_exclusive(x86_lbr_exclusive_pt); |
| } |
| |
| static int pt_event_init(struct perf_event *event) |
| { |
| if (event->attr.type != pt_pmu.pmu.type) |
| return -ENOENT; |
| |
| if (!pt_event_valid(event)) |
| return -EINVAL; |
| |
| if (x86_add_exclusive(x86_lbr_exclusive_pt)) |
| return -EBUSY; |
| |
| event->destroy = pt_event_destroy; |
| |
| return 0; |
| } |
| |
| void cpu_emergency_stop_pt(void) |
| { |
| struct pt *pt = this_cpu_ptr(&pt_ctx); |
| |
| if (pt->handle.event) |
| pt_event_stop(pt->handle.event, PERF_EF_UPDATE); |
| } |
| |
| static __init int pt_init(void) |
| { |
| int ret, cpu, prior_warn = 0; |
| |
| BUILD_BUG_ON(sizeof(struct topa) > PAGE_SIZE); |
| |
| if (!test_cpu_cap(&boot_cpu_data, X86_FEATURE_INTEL_PT)) |
| return -ENODEV; |
| |
| get_online_cpus(); |
| for_each_online_cpu(cpu) { |
| u64 ctl; |
| |
| ret = rdmsrl_safe_on_cpu(cpu, MSR_IA32_RTIT_CTL, &ctl); |
| if (!ret && (ctl & RTIT_CTL_TRACEEN)) |
| prior_warn++; |
| } |
| put_online_cpus(); |
| |
| if (prior_warn) { |
| x86_add_exclusive(x86_lbr_exclusive_pt); |
| pr_warn("PT is enabled at boot time, doing nothing\n"); |
| |
| return -EBUSY; |
| } |
| |
| ret = pt_pmu_hw_init(); |
| if (ret) |
| return ret; |
| |
| if (!pt_cap_get(PT_CAP_topa_output)) { |
| pr_warn("ToPA output is not supported on this CPU\n"); |
| return -ENODEV; |
| } |
| |
| if (!pt_cap_get(PT_CAP_topa_multiple_entries)) |
| pt_pmu.pmu.capabilities = |
| PERF_PMU_CAP_AUX_NO_SG | PERF_PMU_CAP_AUX_SW_DOUBLEBUF; |
| |
| pt_pmu.pmu.capabilities |= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE; |
| pt_pmu.pmu.attr_groups = pt_attr_groups; |
| pt_pmu.pmu.task_ctx_nr = perf_sw_context; |
| pt_pmu.pmu.event_init = pt_event_init; |
| pt_pmu.pmu.add = pt_event_add; |
| pt_pmu.pmu.del = pt_event_del; |
| pt_pmu.pmu.start = pt_event_start; |
| pt_pmu.pmu.stop = pt_event_stop; |
| pt_pmu.pmu.read = pt_event_read; |
| pt_pmu.pmu.setup_aux = pt_buffer_setup_aux; |
| pt_pmu.pmu.free_aux = pt_buffer_free_aux; |
| ret = perf_pmu_register(&pt_pmu.pmu, "intel_pt", -1); |
| |
| return ret; |
| } |
| arch_initcall(pt_init); |